PATENT LITERATURE 6 discloses a system in which a traction roller is inserted in a space between disks opposed to and arranged to rotate reversely to each other to form an infinitely variable speed converter. In this case, there is no description of a motor for driving the disks, which are arranged to rotate reversely to each other, and thus the relationship between the disk plates and the motor is not described clearly.
PATENT LITERATURE 2 discloses an infinitely variable speed converter having multiple thin dynamo/motors of large diameter joined via a central shaft and arranged to rotate reversely to each other for use as driving motors in an electric vehicle, in which a traction roller penetrated by a drive shaft is inserted in a space between a friction plate serving as a side plate of a rotor of an upper driving motor and a friction plate serving as a side plate of a rotor of a lower driving motor in such a manner as to come into contact with the upper and lower friction plates, whereby the traction roller is rotated and a torque is output to the drive shaft. In the literature, the friction plates that form the space in which the traction roller is inserted are described for the rotors of the respective upper and lower motors, indicating that the dynamo/motors are independent of and separated from each other. Accordingly, the infinitely variable speed converter is constituted, in the direction of the central shaft, by at least three structures of the at least two independent dynamo/motors and the variable transmission occupying the space between the dynamo/motors in the direction of the central shaft and, when installed, for example, under the floor of the cabin in a vehicle as a device for driving the vehicle, occupies a space of about 50 cm or more, imposing a limitation due to the thickness of the entire device in the direction of the central shaft of the dynamo/motors, such as that the height of the cabin floor in the vehicle has to be set to a significantly higher position compared to that of the driver's seat.
PATENT LITERATURE 4 discloses a dynamo/motor inside and/or around which traction gears are disposed to allow for speed conversion with a compact mechanism. PATENT LITERATURE 5 discloses a drive system in which a group of traction gears around a dynamo/motor are switched effectively so that the entire drive system is compactified and settled with the dynamo/motor centered thereon.
PATENT LITERATURE 3 discloses a toroidal core motor system having a large diameter to be thinned easily in the direction of a central shaft. In the case of conventional ways for forming an armature by punching magnetic steel, since common magnetic steel sheets have a size of about 60 cm square, it is difficult to form a motor having a diameter greater than about 60 cm. Toroidal core motors, which can employ a wound core, can be fabricated easily to have a large diameter greater than about 60 cm. On the other hand, it is however difficult to mount a wound core used in such toroidal core motors to a shroud (including an exterior portion such as a housing or a case and an interior portion if the wound core is arranged to rotate), unlike the case of punching lamination for magnetic steel. In PATENT LITERATURE 3, amounting tool serving also as a magnetic pole portion is used to, for example, bore a mounting hole in the wound core, whereby the wound core can be mounted to the shroud with no property degradation. In particular, PATENT LITERATURE 3 provides an example for the mounting tool serving also as the magnetic pole portion that is clearly specified in Paragraph 0050 and FIG. 13, in which almost half of the mounting tool serving also as the magnetic pole portion is composed of non-magnetic material. This is of great help to the case where the distance between a toroidal core and a target to which the toroidal core is mounted is very large as in the present invention because magnetic material can be saved.
PATENT LITERATURE 1, which has not yet been published up to now, describes a dynamo/motor with built-in speed converter similar to one according to the present invention. In the present invention, three examples are added to PATENT LITERATURE 1.